1. Field of Invention
The present invention pertains to the field of information systems. More particularly, this invention relates to a method and apparatus for analyzing the performance of an information system.
2. Art Background
An information system commonly includes one or more servers and related resources that provide information services to one or more users. Such servers may include web servers, email servers, proxy servers, or other types of servers depending on the nature of information services being provided. Typically, each user employs a computer or other access device to access information from the servers.
Providers of information services commonly seek to assess the quality of service being provided to their users in terms of performance. Such an assessment of performance if available would be useful for a variety of applications. For example, an assessment of performance may be useful for determining whether additional capacity is needed in the information system. In addition, an assessment of performance may be useful in providing service guarantees to users or in generating alarm conditions whenever the assessed performance falls below a desired performance level.
An assessment of the performance of an information system may be based on one or more of a variety of measurements such as data throughput or response time to user requests, etc. It is usually preferable that an assessment of performance apply the aggregate of users because the time and costs involved in tracking the performance for each and every user may be prohibitive.
One prior method for assessing the performance of an information system is to retrieve and analyze the information contained in subscriber logs which are commonly maintained in servers. These subscriber logs usually include information such as the time of access, subscriber addresses, the data transfer size, and the total time for the data transfer for each data transfer.
Unfortunately, it is usually not easy to assess the performance being provided to the aggregate of users from the information contained in subscriber logs. For example, differing users commonly engage in server communication using differing data transfer sizes. In addition, differing users commonly use computers having differing system performance, differing configurations, and differing network connection speeds. This variability among users usually makes it difficult to apply the information contained in a subscriber log toward a meaningful assessment regarding the aggregate of users. Moreover, transient periods of relatively high or relatively low server accesses can distort the information contained in subscriber logs in terms of a meaningful assessment of the performance of an information system.